WO2008/149061 (Cox Powertrain) describes a 2-cylinder 2-stroke direct injection internal combustion engine. The two cylinders are horizontally opposed and in each cylinder there are opposed, reciprocating pistons that form a combustion chamber between them. The pistons drive a central crankshaft between the two cylinders. The inner piston (i.e. the piston closer to the crankshaft) in each cylinder drives the crankshaft through a pair of parallel scotch yoke mechanisms. The outer piston in each cylinder drives the crankshaft through a third scotch yoke, nested between the two scotch yoke mechanisms of the inner piston, via a drive rod that passes through the centre of the inner piston. The drive rod has a hollow tubular form and fuel is injected into the combustion chamber by a fuel injector housed within the drive rod. The wall of the drive rod has a series of circumferentially spaced apertures through which the fuel is projected laterally outwardly into the combustion chamber.
WO2012/160378 (Cox Powertrain) describes a development of the configuration of the engine described in WO2008/149061. In the engine described in this document, the outer piston of each pair of opposed pistons drives the crankshaft through a drive linkage that is external to the cylinder in which the pistons reciprocate. This avoids the need for any drive rods passing through the combustion chamber and inner piston and also means that a fuel injector can be located centrally with respect to the piston (or close to the centre of the piston) without obstruction.